1. Field of the Invention
The present invention relates to disk drives. In particular, the present invention relates to a head stack assembly comprising a multi-level shipping comb to facilitate merging heads with disks.
2. Description of the Prior Art
FIG. 1 shows a prior art disk drive comprising a disk stack having at least one disk 4 and a head stack assembly (HSA) 6 installed in a base casting 8 which is enclosed by a cover 10 to form a head disk assembly (HDA). The HSA 6 comprises a number of actuator arms 12 which are rotated about a pivot 13 by a voice coil motor (VCM) 14. A suspension 16 is attached to the distal end of each actuator arm 12, and a head 18 is attached to the distal end of the suspension 16. The suspension 16 biases the head 18 toward the surface of the disk 4, and as the disk 4 rotates about its center axis an air bearing forms between the head 18 and the disk 4 so that the head 18 flies just above the disk 4 during read/write operations. When manufacture the disk drive 2, the HSA 6 is installed into the base casting 8 such that the actuator arms 12 fit into gap 20. The actuator arms 12 are then rotated about the pivot 13 in order to “merge” the heads 18 with the respective disk surfaces.
After the HSA 6 is manufactured, a shipping comb is attached to protect the suspension 16 during storage and shipping. For example, with an HSA comprising multiple suspensions (FIG. 3) the shipping comb prevents the suspensions from colliding into one another. The shipping comb also protects the suspensions from overstressing. FIGS. 2A and 2B show a prior art shipping comb 22 which has a pin 24 that is inserted through an aperture 26 in the actuator arm 12. A latching member 28 secures the shipping comb 22 to the actuator arm 12 and a finger 30 maintains the suspension 16 in a near optimal vertical position. The vertical movement of the head 18 is also limited by a tab 32 to protect against head damage. Only the bottom suspension 16 and head 18 are shown in FIGS. 2A and 2B, the top suspension and head are not shown for clarity. FIG. 3 shows a prior art shipping comb 32 comprising a plurality of fingers 34 for maintaining a number of top and bottom suspensions in a near optimal vertical position during storage and shipping.
To facilitate installing the HSA 6 when manufacturing the disk drive a merge tool is employed to hold the suspension 16 in place while the actuator arm 12 is rotated to position the head 18 over the surface of the disk 4. Referring again to FIGS. 2A and 2B, after the merge tool engages the suspension 16, the shipping comb 22 is rotated (clockwise in FIG. 2B) to detach the shipping comb 22 from the actuator arm 12 prior to performing the merge. A problem with this prior art technique, however, is that when the merge tool engages the suspension 16 from the side the merge tool can scrape the suspension 16 causing damage to the suspension 16 as well as particle contamination. The particles generated from scraping can also contaminate the merge tool thereby affecting other drives since the merge tool is re-used to manufacture multiple drives.
There is, therefore, a need for a disk drive shipping comb that protects the suspension from damage when a merge tool engages the suspension during the merge operation.